Short stature commonly follows intrauterine growth retardation (IUGR). Most patients are not growth hormone (GH)-deficient, but GH therapy has been used in IUGR. Early studies found a heterogeneous increase in initial growth rate that could not be maintained. Results of more recent studies with higher doses are more encouraging but do not establish whether final height is increased. Data from a large number of patients in the National Cooperative Growth Study were reviewed to evaluate the response to GH treatment in patients with IUGR-associated short stature. Two hundred seventy such patients were identified and were categorized as those with unclassified IUGR and those with Russell-Silver syndrome/primordial short stature (RSS/PSS). Patients were treated with standard doses of recombinant human GH (approximately 0.3 mg/kg per week) and were assessed periodically for up to 4 years. The height SD score at baseline in patients with unclassified IUGR was -3.49 +/- 1.16, and their relative height improved with each year of therapy. Patients who completed 4 years of treatment reached a height SD score of -1.32 +/- 0.79. Results were similar in patients with RSS/PSS; their baseline height SD score was -3.83 +/- 1.05 and improved to -2.10 +/- 0.99 by year 4. Despite these encouraging results, no change occurred in predicted adult heights. Furthermore the number of patients who remained in treatment for 4 years decreased substantially, thus limiting the interpretation of the data. These data suggest that a beneficial response to GH occurs in some patients with IUGR-associated short stature and that little difference exists in the responses in patients with RSS/PSS compared with those in patients with unclassified IUGR.